1. Field of the Invention
The present application relates to an adhesive material, and more particular to an insulating adhesive material having high heat conductivity and superior impact resistance.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
The light emitting diodes (LEDs) have been used since 1960s, and usually used as indicating or signal lights. Because traditional LEDs do not have high power consumption, heat dissipation of LED packaging was not an issue. In recent years, lightness and power consumption of the LEDs used for television backlights or illumination have become increasingly high, and therefore heat dissipation becomes a crucial problem for LED illumination applications.
A traditional incandescent lamp dissipates about 70% heat by infrared radiation, so that heat accumulation in the lamp is not obvious. However, an LED usually emits visible light or ultraviolent light, and therefore it does not easily dissipate heat by radiation. In addition, small LED packaging area is hard to dissipate heat efficiently, resulting in LED luminous decay. Therefore, heat management is important for LED illumination applications.
Traditionally, LEDs transfer heat to a substrate through a metal lead flame, and thermal resistance of package is very high, e.g., 250-300° C./W. Then, LEDs are surface-mounted on to circuit board for packaging, in which a resin layer (FR4) adhered to the circuit board is used for heat transfer. The large heat dissipation area can significantly decrease thermal resistance. However, FR4 may not be suitable for packaging of high power LED due to its low heat conductivity coefficient. Nowadays, as to LEDs, heat-source devices or other electronic devices, a thermal interface material is employed to combine such devices and a heat dissipation structure. The thermal interface material usually contains an organic silicon polymer, which has low viscosity and good reliability but is costly. Moreover, though the silicon polymer can withstand high temperature, it may generate liquefied residue or outgas caused by material degradation after being used for a certain time period.